Oxygen evolution reaction on lead–bismuth alloys in sulfuric acid solution

Lead–bismuth alloys with bismuth from 0 to 8 wt.% were prepared. Oxygen evolution reaction on the alloys with lead dioxides was investigated by using linear voltammetry, electrochemical impedance spectroscopy, scanning electron spectroscopy, electron diffraction spectroscopy, oxygen collection experiments. The oxygen evolution reaction on the alloys with bismuth content <0.1% is not affected by the bismuth in the alloys. However, the rate of oxygen evolution reaction increases with increasing the bismuth content in the alloys. This is related to the dissolution of bismuth from the alloys to solution and the adsorption of bismuth ions from solution onto the surface of lead dioxide. Unlike lead, bismuth can dissolve into solution under anodic polarization. At the potentials where there is no oxygen evolution, lead–bismuth alloys are well passivated by lead sulfate or lead dioxide. The lead dioxide on the alloys becomes porous when oxygen evolution takes place on it, thus bismuth in the alloys dissolves. The amount of dissolved bismuth increases with the bismuth content in the alloys and the adsorption of bismuth ions onto lead dioxide takes place when bismuth ion concentration near the oxide surface is high enough. The lead dioxide with adsorbed bismuth ions can accelerates oxygen evolution reaction and oxygen evolution increases with increasing the amount of adsorbed bismuth ions.